Crystal chemistry, Raman and FTIR spectroscopy, optical absorption, and luminescence study of Fe-dominant sogdianite

Abstract

Fe-dominant sogdianite, a cyclosilicate compound with the chemical formula (Fe³⁺ _0.74Zr_0.64Ti_0.46 Al_0.15)(□_1.02Na_0.98)K[Li₃Si₁₂O₃₀], was studied. The investigation involved a comprehensive analysis of the mineral sample, including crystal-chemical analysis, Raman and FTIR spectroscopy, optical absorption, and luminescence study. Crystallographic site populations were determined through single crystal structure refinement and electron probe microanalysis. The thermoelastic behavior of a powder was studied using in situ high-temperature X-ray diffraction (30–750 °C). Notably, no phase transition was detected; sogdianite exhibited anisotropic thermal expansion. The first time study of vibrational spectra and spectral bands assigning were performed. The electronic transitions in d ⁵-ion impurities of sogdianite were studied using optical absorption and luminescence spectroscopy. The origin of pink color and luminescence of sogdianite was clarified. The broad spectral bands in the visible UV spectral region are responsible for the pink color exhibited by sogdianite and could be attributed to d–d transitions occurring in Fe³⁺ ions.